echo that outputs to stderr – Dev

The best answers to the question “echo that outputs to stderr” in the category Dev.

QUESTION:

Is there a standard Bash tool that acts like echo but outputs to stderr rather than stdout?

I know I can do echo foo 1>&2 but it’s kinda ugly and, I suspect, error prone (e.g. more likely to get edited wrong when things change).

ANSWER:

You could define a function:

echoerr() { echo "[email protected]" 1>&2; }
echoerr hello world

This would be faster than a script and have no dependencies.

Camilo Martin’s bash specific suggestion uses a “here string” and will print anything you pass to it, including arguments (-n) that echo would normally swallow:

echoerr() { cat <<< "[email protected]" 1>&2; }

Glenn Jackman’s solution also avoids the argument swallowing problem:

echoerr() { printf "%s\n" "$*" >&2; }

ANSWER:

You could do this, which facilitates reading:

>&2 echo "error"

>&2 copies file descriptor #2 to file descriptor #1. Therefore, after this redirection is performed, both file descriptors will refer to the same file: the one file descriptor #2 was originally referring to. For more information see the Bash Hackers Illustrated Redirection Tutorial.

ANSWER:

Another option

echo foo >>/dev/stderr

ANSWER:

Since 1 is the standard output, you do not have to explicitly name it in front of an output redirection like >. Instead, you can simply type:

echo This message goes to stderr >&2

Since you seem to be worried that 1>&2 will be difficult for you to reliably type, the elimination of the redundant 1 might be a slight encouragement to you!